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Abstract

A characteristic spectral emission is observed in veg-etation chlorophyll under excitation by solar radiation. This emission, known as solar-induced chlorophyll flu-orescence, occurs in the red and near infra-red spectral regions. In this paper a new methodology for the es-timation of solar-induced chlorophyll fluorescence from spaceborne and airborne sensors is presented. The flu-orescence signal is included in an atmospheric radiative transfer scheme so that chlorophyll fluorescence and sur-face reflectance are retrieved consistently from the mea-sured at-sensor radiance. This methodology is tested on images acquired by the Medium Resolution Imag-ing Spectrometer (MERIS) on board the ENVIronmental SATellite (ENVISAT) taking advantage of its good char-acterization of the O2-A absorption band. Validation of MERIS-derived fluorescence is carried out by applying the method to data acquired by the Compact Airborne Spectrographic Imager (CASI-1500) sensor concurrently to MERIS acquisitions. CASI-derived fluorescence is in turn compared with ground-based fluorescence measure-ments. A correlation coefficient R2 of 0.85 is obtained. Key words: Solar-induced chlorophyll fluorescence, Re-mote sensing, Atmospheric correction, Vegetation in-dices.